Add check for static class objects in Node::mayModifyValue #7294
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This commit fixes a segmentation fault that occurs during side effect detection in IL generation for an edge case a static class object reference is passed in as an argument to Node::mayModifyValue. Node::mayModifyValue assumes that if its opcode is a store, the symbol reference whose value it modifies must be one of: + auto + parm + static field ref Because of the way that side effects of nodes are checked by recursively traversing their children (see J9ByteCodeIlGenerator::valueMayBeModified) and the way certain IL is generated, it is possible that these assumptions are not invariant. In a concrete case, when a awrtbar is generated for static stores, one of the awrtbar children will be a loadaddr which loads a static class object. When this case occurs, node::mayModifyValue will erroneously use the constant pool index of the static class reference as a static field reference, eventually resulting in a garbage value and causing a segmentation fault. Fixes: #18156 Signed-off-by: James You <james.you@protonmail.com>
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This commit fixes a segmentation fault that occurs during
side effect detection in IL generation for an edge case
a static class object reference is passed in as an argument
to Node::mayModifyValue.
Node::mayModifyValue assumes that if its opcode is a store,
the symbol reference whose value it modifies must be one of:
Because of the way that side effects of nodes are
checked by recursively traversing their children
(see J9ByteCodeIlGenerator::valueMayBeModified)
and the way certain IL is generated,
it is possible that these assumptions are not invariant.
In a concrete case, when a awrtbar is generated for static stores,
one of the awrtbar children will be a loadaddr which loads
a static class object. When this case occurs, node::mayModifyValue
will erroneously use the constant pool index of the static class reference
as a static field reference, eventually resulting in a garbage value
and causing a segmentation fault.
Fixes: eclipse-openj9/openj9#18156